An interesting thing has come to my attention as I browse photos of MD-11s in action. It appears that while the MD-11 is able to use both inboard and outboard ailerons simultaneously as flaperons, to augment flap function much as the 777 does, in some cases, it is clear that they are not used, and the MD-11 wing in those cases appears to function exactly as its predecessor, the DC-10 (i.e. just flaps, while inboard and outboard ailerons are flush).

Why is this? What flight management decision governs whether a crew will program the system to droop ailerons for flap augmentation, or not?

May the wind be always at your back . . . except during takeoff & landing.

Interesting. I had another thought after posting: Maybe using more trailing edge flap but no aileron deflection (e.g. 30º flap for takeoff) would mean that a tailstrike on takeoff would be less likely than if you used, say, 10º flap + aileron deflection.

Just a thought.

May the wind be always at your back . . . except during takeoff & landing.